Novel collectors and processes for making and using same

ABSTRACT

A method for the production of alkyl or alkaryl hydroxamic acids and/or salts wherein a C 8  -C 22  alcohol is employed with water as the solvent is disclosed as well as the resultant salt and/or acid solutions per se and their use in the flotation of non-sulfide minerals, preferably clay.

This is a divisional of co-pending application Ser. No. 07/108,611,filed on Oct. 15, 1987 now U.S. Pat. No. 4,871,466.

BACKGROUND OF THE INVENTION

Alkyl or alkaryl hydroxamic acids and their salts are well-knowncollectors for the froth flotation of oxide minerals. Soviet workershave found a variety of applications for such alkyl hydroxamic acids. Arecent review summarizes the flotation application of alkyl hydroxamicacids (Pradip and Fuerstenau, "Mineral Flotation with HydroxamateCollectors", in "Reagents in the Minerals Industry", Ed. M. J. Jones andR. Oblatt, Inst. Min. Met., London, 1984, pp. 161-168). Hydroxamic acidshave been used for the flotation of metals or minerals such aspyrochlore (Nb, Ta), fluorite, huebnerite, wolframite, cassiterite,muscovite, phosphorite, hematite, pyrolusite, rhodonite, chrysocolla,malachite, barite, calcite, and rare-earths. They are generally morepowerful and more selective than conventional fatty acids, fatty amines,petroleum sulfonates and alkyl sulfates. However, the commerciallyemployed methods of making alkyl or alkaryl hydroxamic acid or its saltsare tedious, and unsafe from the point of view of industrial production.For example, Organic Synthesis, Vol. II, page 67 sets forth a procedurefor making potassium alkyl hydroxamate wherein a methanol solution ofKOH (56 gm in 140 cc of methanol) and another of NH₂ OH HCl (41.7 gm in240 cc of methanol) are combined. The KCl by-product is filtered off. Tothe filtrate is added 56.1 gm of a mixed liquid of methylcaprylate/caprate. After standing 24 hours, the product crystals (50 gm,or 67% yield) are filtered off. A major drawback of this method is theuse of a large amount of methanol which is toxic and flammable. Anotherdrawback is the use of potassium hydroxide which is more expensive thansodium hydroxide. Furthermore, the filtration of methanolic reactionmixture on an industrial scale is obviously not desirable in terms ofsafety. Finally, the yields are quite low.

Hartlage (U.S. Pat. No. 3,933,872, Jan. 20, 1976) claims an improvedmethod of making fatty hydroxamates. Dimethylamine is used to effect thereaction between hydroxylamine sulfate and the methyl ester of a fattyacid in an anhydrous lower alcohol slurry. The free hydroxamic acidsformed are neutralized with dimethylamine or an alkali metal base toyield, after filtering and drying, the ammonium or alkali metal saltprecipitate. The procedure given, however, still employs flammable loweralcohols, i.e., methanol, ethanol or isopropanol. Furthermore, becauseof the heterogeneous nature of the reaction, the reaction rate is veryslow, e.g., 15 hours in methanol and 5 days in isopropyl alcohol andfiltration of the final hydroxamate product is still necessary. In anoperation when methanol, a toxic flammable liquid, is employed, ahazardous environment is created. Finally reported yields are only inthe 75-76% range.

Various Russian workers have reported methods for making alkylhydroxamic acids and/or their salts in aqueous alkaline media. Sodiumalkyl hydroxamates were made by reacting the methyl ester of a C₇₋₉carboxylic acid with an aqueous solution of hydroxylamine sulfate andNaOH at a molar ratio of 1:1.22:2.2 and a temperature of 55° C. or below(Gorlovski, et. al. Vses. Soveshch. po Sintetich. Zhirozamenitelyam,Poverkhnostnoaktivn, Veschestvam i Moyushchim Sredstvam, 3rd, Sb.,Shebekino, 1965, 297-9 Chem. Abst. 66, 4983h, 1967). A yield of only72-78% of the free C₇₋₉ hydroxamic acid was reported by Shchukina et.al. (Khim. Prom., Moscow, 1970. 49(3) 220) by reacting one mole of themethyl ester, 1.45 mole hydroxylamine sulfate, 7.39-7.82 moles NaOH fortwo hours at 20°-25° C. and one hour at 55°-60° C., followed byacidification to pH 4-5 at temperatures below 40° C. Again, in Sin.Primen. Novykh Poverkh. Veshchestv, 1973, 123-31 reported in C.A. 80,1974, 95199k, Shchukina et al report a simple lab method for theproduction of a reagent designated as IM-50 from C₇₋₉ esters. In aRussian Patent (U.S.S.R. No. 390,074, July 11, 1973 Chem. Abst. 79,115162C (1973)) and also in an article (Zh. Prikl. Khim, (Leningrad)1972 45(8), 1895-7, Chem. Abstract 78. 29193m 1973), Russian workersreported improved yields with the use of 3-5% of an anionic emulsifierin an alkaline aqueous medium. The authors reported that the use of ananionic surfactant such as sodium lauryl sulfate (3-5% based on theweight of the methyl ester), gave an improved yield of 61.2% forvalerihydroxamic acid and 89% for caprihydroxamic acid. To obtain theyields claimed, however, a 40 molar % excess of hydroxylaminehydrochloride or sulfate was required. Furthermore, both the sodiumslats and the free hydroxamic acids recovered are solids which aredifficult to handle and process.

In another Russian patent (U.S.S.R. 513,970, May 15, 1976, Chem. Abst.85, 66277 g, 1976) a solution of mixed free C₈₋₁₁ hydroxamic acids wasobtained in hydrocarbons. This was achieved by treating the sodiumalkylhydroxmates with a mineral acid in the presence of 100-250 weightpercent of a hydrocarbon containing less than 20% polar organiccomponents (e.g., higher alcohols or esters). The aqueous layercontaining NaCl or Na₂ SO₄ was discarded as effluent.

Finally, U.S. Pat. No. 4629556 has recently issued wherein variouscolored impurities are removed from kaolin clays utilizing alkyl, arylor alkylaryl hydroxamates as collectors. The hydroxamates are disclosedas having been produced by reacting free hydroxylamine with the methylester of an organic acid of appropriate hydrocarbon chain length andconfiguration in a non-aqueous medium such as methanol much in the samemanner as taught in the above-mentioned articles.

While these reports certainly represent advancement of the art, thereare still many drawbacks regarding industrial production. On a largescale of production, for example, the aqueous effluent can besubstantial and can pose a serious problem for disposal. Furthermore, inorder to obtain a product in liquid form, the alkali metal alkylhydroxamates must be acidified to the free hydroxamic acids. Thisacidification is an additional step and causes a substantial increase inprocessing and handling time and costs. The use of anionic surfactantsas taught by the Russians also causes a foaming problem duringmanufacture.

SUMMARY OF THE INVENTION

It has now been found that useful alkali metal alkyl hydroxamates can beproduced by reacting the methyl or ethyl ester of a fatty acid having6-22 carbon atoms with a hydroxylamine salt and an alkali metalhydroxide in the presence of a water/C₈ -C₂₂ alcohol mixture, preferablyin the presence of a non-ionic or cationic surfactant. This procedureresults in the formation of a liquid solution of the hydroxamate whichcan be used as such in the froth flotation of non-sulfide minerals suchas kaolin clays or neutralized to form a liquid alcohol solution of theacid which may also be so utilized. The instant process of producing thealkali metal alkyl hydroxamate salts and acids eliminates the need forhazardous and expensive recovery steps such as filtration; it isrelatively rapid, i.e., the reaction is complete in 3-5 hours; and itresults in extremely high conversions, i.e., 85-95%, in the absence offoaming. When a surfactant is used, the instant process requires lesseramounts thereof than shown in the art.

Furthermore, when utilized in the froth flotation of non-sulfideminerals, the alcohol solutions of the hydroxamates and hydroxamic acidsare significantly more effective than prior art compositions such asIM-50.

DESCRIPTION OF THE INVENTION INCLUDING PREFERRED EMBODIMENTS

As discussed briefly above, the instant invention resides in a methodfor the production of a salt of a fatty hydroxamic acid or the fattyhydroxamic acid per se by reacting a methyl or ethyl ester of a fattyacid having 6-22 carbon atoms, preferably at least 8 carbon atoms, witha hydroxylamine salt and an alkali metal hydroxide in the presence ofwater, a C₈ -C₂₂ alcohol, preferably an alcohol of at least 10 carbonatoms. The reaction proceeds according to the equation: ##STR1## whereinR is a C₆ -C₂₂ alkyl, an aryl (C₆ -C₁₀) or an alkaryl (C₇ -C₁₄) group, Mis an alkali metal and R¹ is methyl or ethyl.

Useful acid esters include the methyl and ethyl esters of suchcarboxylic acids as caproic acid (C₆), enanthic acid (C₇), caprylic acid(C₈), pelargonic acid (C₉), caproic acid (C₁₀), undecanoic (C₁₁), lauric(C₁₂), tridecanoic (C₁₃), myristic (C₁₄), pentadecanoic acid (C₁₅),palmitic acid (C₁₆), margaric acid (C₁₇), stearic acid (C₁₈) and thelike. Oleic acid (C₁₈), benzoic acid, ethyl benzoic acid, salicylicacid, α-and β-naphthoic acid, cyclohexyl carboxylic acid, cyclopentylcarboxylic acid etc. are additional examples. Ethyl esters of abovecarboxylic acids require a higher reaction temperature than the methylesters.

Hydroxylamine salts such as the sulfate or hydrochloride etc., can beused. Suitable alkali metal hydroxides include NaOH, KOH etc. Aminessuch as ammonia, dimethylamine etc. can be used in place of thehydroxides.

As mentioned above, a non-ionic or cationic surfactant is alsopreferably used. Exemplary surfactants include non-ionic surfactantssuch as alkyl polyethyleneoxy compounds represented by the formula:

    RO(EO)--H

wherein R is C₈ -C₁₈ alkyl, EO is ethyleneoxy and n is a number from 1to 10. Additional non-ionic surfactants include the reaction products ofethylene oxide and higher alkylene oxide with active hydrogen compoundssuch as phenols, alcohols, carboxylic acids and amines, e.g.,alkylphenoxyethyleneoxy ethanols. Suitable cationic surfactants arethose such as alkyl ammonium or quaternary ammonium salts, e.g.,tetraalkyl ammonium chloride or bromide, dodecyl ammonium hydrochloride,dodecyl trimethyl quaternary ammonium chloride and the like, andethoxylated fatty amines. Other suitable surfactants are described inMcCutcheon's book of detergents and emulsifiers. Also included in theaforementioned surfactants are oligomeric and polymerizable surfactantsdescribed at pages 319-322 of Blackley, Emulsion Polymerization Theoryand Practice, John Wiley and Sons (1975). Examples of such oligomersinclude ammonium and alkali metal salts of U functionalized oligomerssold by Uniroyal Chemical under the trade name "Polywet" and copolymersof acrylonitrile and acrylic acid having molecular weights less than2000 which are prepared in the presence of chain terminating agents suchas n-octyl mercaptan. Examples of polymerizable surfactants includesodium salts of 9- and 10-(acrylylamido)stearic acid and the like. Theeffective amounts of the surfactant range from about 0.5 to 3%, byweight, of the alkyl ester, preferably about 1.0%-2.0%, by weight, samebasis.

The higher alkyl alcohols are the C₈ -C₂₂ alcohols, preferably C₁₀ -C₁₈alcohols. They can be linear or branched. Examples include octylalcohol, nonyl alcohol, decyl alcohol, undecyl alcohol, dodecyl alcohol,tridedecyl alcohol, tetradecyl alcohol, pentadecyl alcohol, hexadecylalcohol, heptadecyl alcohol, stearic alcohol and the like. Thesealcohols may be used individually or as mixtures. The amount needed toeffect a clear liquid varies according to the alcohol used, thehydroxamate to be made and the amount of water present. Based onquasi-elastic light scattering experiments, the clear liquids producedin the process of the invention were found, in reality, to be in a clearmicroemulsion form. Their stability is, therefore, a equilibrium balancebetween all of the components present. A generally useful guideline is75-175 parts of alcohol per 100 parts of alkyl ester. For decyl alcohol,for example, the weight range can be 90 parts to 150 parts per hundredparts of the alkyl ester, preferably 115 to 138 parts. The concentrationof the aqueous solution of hydroxylamine salt may vary from about about15 to 35%, preferably from about 25-30%, by weight. The calculatedamount of alkali used should be at least sufficient to both liberate thefree hydroxylamine from its salts and to neutralize the free hydroxamicacid, although excess amounts (5-15%) may be used. The molar ratio ofhydroxylamine salt to the ester should range from about 1:1 to 1.10:1.0.Excess amounts of hydroxylamine salt greater than 10% can be used butare not necessary and no beneficial result has been observed using suchexcess amounts.

The reaction temperature can range from about 15 to 55° C., preferablyfrom about 25° to 35° C.

Sufficient water is used to dissolve the hydroxylamine salt. The amountof water used generally depends upon the concentration of thehydroxylamine salt solution. Water in the final hydroxamate salt productcan vary from about 30-50%.

The instant invention is also directed to the novel compositionsproduced by the above-described process. These compositions comprise, ifno neutralization of the product is conducted, a water/alcohol solution,the alcohol containing 8-22 carbon atoms, of the fatty hydroxamic acidsalt, an alkali metal sulfate and preferably include a cationic ornon-ionic surfactant. The solution will contain from about 10% to about30% of the acid salt, from about 5% to about 10% of the sulfate, fromabout 0.0% to about 0.6% of the surfactant and water as indicated above.Minor or trace amounts of other ingredients which in no way modify oralter the final product may also be present.

When the above product is neutralized by the addition of acid wherebytwo phases are formed, the aqueous phase is removed such as bydecantation or as described in U.S. Pat. No. 3,933,872, incorporatedherein by reference. The organic phase results in the second novelcomposition of the present invention comprising a C₈ -C₂₂ alcoholsolution of the fatty hydroxamic acid and preferably the cationic ornon-ionic surfactant. The acid content ranges from about 30% to about70% and the surfactant ranges from about 0.0% to about 0.0%.

The above-described compositions are useful in the frother flotation ofnon-sulfide mineral ores such as those mentioned above and includingcopper ores, iron ores, rare and rare earth metal ores and, moreparticularly, in the beneficiation of clays.

Useful flotation methods are those well-known and established to thoseskilled in the art. In general, the methods comprise, firstly, the stepof grinding of the ore to provide liberation of mineral values and oreparticle size suitable for flotation. Secondly, the ground ore pulp ispH-adjusted, and conditioned with pre-selected and prescribed reagentssuch as collectors, frothers, modifiers, and dispersants. With someores, the as-mined feed material is already finely divided and,therefore, no additional grinding is involved. Examples are glass sands,clays, tailings etc.

In the case of clays beneficiation for example, substantially nogrinding of the as-mined feed is required since the average particlesize is of the order of a few microns. The major impurities in kaolinclays are anatase (TiO₂) and complex iron minerals. These impuritiesimpart color to the clay and decrease its brightness, thus making theclay unsuitable for many of its applications where purity and brightnessare absolutely essential. Conventionally, the removal of such impuritiesis accomplished by a variety of methods, an important one beingflotation using tall oil fatty acid.

In the froth flotation for beneficiating clay wherein the clay isslurried in an aqueous medium, conditioned with an effective amount of adispersing agent and collector and floated, the instant inventioncomprises employing, as the collector, the novel compositions above,i.e., the hydroxamic acid/alcohol solution or the hydroxamic acidsalt/water/alcohol solution in quantities ranging from about 0.1 toabout 18.0 pounds per ton of ore, preferably 0.5-6 pounds per ton. Thenovel process of the present invention results in the recovery of claysin high yields, of low TiO₂ content and increased brightness.

As a first step in carrying out such a process, the clay to be purifiedis blunged in water at an appropriate solids concentration as describedin U.S. Pat. No. 4,629,556, incorporated herein by reference. Arelatively high pulp density, in the range of 35-70% solids, by weight,is preferred since the interparticle scrubbing action in such pulpshelps liberate colored impurities from the surfaces of the clayparticles.

Following conventional practice, a suitable dispersant, such as sodiumsilicate, polyacrylate, or polyphosphate, is added during blunging in anamount, e.g., 1-20 lb. per ton of dry solids, sufficient to produce awell-dispersed clay slip. An alkali, such as ammonium hydroxide, is alsoadded as needed to produce a pH above 6 and preferably is the range of8-10.5. The hydroxamate collector, in accordance with the invention, isthen added to the dispersed clay under conditions, i.e., properagitation speed, optimum pulp density, and adequate temperature, whichpermit reaction between the collector and the colored impurities of theclay in a relatively short time, generally not longer than 5-10 minutes.

When the clay has been conditioned after the addition of collector, itis transferred to a flotation cell and is usually diluted to a pulpdensity preferably in the range of about 15-45% solids, by weight. Theoperation of the froth flotation machine is conducted in conventionalfashion. After an appropriate period of operation, during which thetitaniferous impurities are removed with the foam, the clay suspensionleft in the flotation cell can be leached for the removal of residualiron oxides, filtered, and dried in conventional fashion.

The following examples are set forth for purposes of illustration onlyand are not to be construed as limitations on the present inventionexcept as set forth in the appended claims. All parts and percentagesare by weight unless otherwise specified.

EXAMPLE 1

In a suitable three-neck reaction vessel, equipped with a condenser, amechanically-driven stirrer and a thermometer, 180.8 parts ofhydroxylamine sulfate are dissolved in 448 parts of water. 475 Parts ofcommercial decyl alcohol (contains 95% trimethyl-1-heptanols and 5%other homologous primary alcohols), 7.4 parts of a 50% dioctyl/decyldimethyl ammonium chloride surfactant, and 337.2 parts of methylcaprylate/caprate are introduced. With stirring, the reaction mixture iscooled to 10°-15° C. with an ice/water bath. Sodium hydroxide (336 partsof 50% NaOH) is added slowly through an addition funnel. The temperatureis kept at 15°-20° C. throughout the addition. After the causticaddition, the temperature is allowed to rise to 25° C. and the reactionis continued for 2-3 hours at 25°-30° C. The reaction is complete whenthe IR spectrum of the reaction mixture shows no trace of the ester band(1175 cm⁻¹). The clear liquid, by UV U analysis (FeCl 3 method), gives ahydroxamate content of 20.3% vs. theoretical 21.5%. This represents a94.4% conversion of the ester into the sodium hydroxamate salt. Thetotal weight of the liquid is 1,775 parts or a 99.5% recovery of thetotal charge and is composed of a capryl/capra hydroxamic acid sodiumsalt, sodium sulfate and dioctyl/decyl dimethylammonium chloride microemulsion in decyl alcohol and water.

EXAMPLE II

The preparation of Example 1 is repeated with the exception of replacingthe cationic surfactant with 4.0 parts of a non-ionic surfactant, anethoxylated nonylphenol (EO=9.5). The emulsion product is a clear liquidhaving a 19.0% hydroxamate content or 87% conversion.

EXAMPLE III

Example I is again repeated except that no surfactant is used. Theliquid product is slightly hazy and, on standing, about 5%, by volume,of an aqueous layer separates on the bottom. Assay gives an 87%conversion to the hydroxamate.

EXAMPLE IV

Example I is again repeated. To the final clear liquid are added 365parts of 27% hydrochloric acid. Two solution phases form and areseparated . The upper organic layer containing the free hydroxamic acid(892 parts) is found, by analysis, to contain 34% free hydroxamic acidvs. 38% theoretical or 89.5% conversion. It is a solution of thecapryl/capra hydroxamic acid in decyl alcohol. The product is compatiblewith tall oil fatty acids.

EXAMPLES V-VII

Example I is again repeated except that the decyl alcohol is replacedwith (V) isooctyl alcohol, (VI) dodecyl alcohol and (VII) a 1:1 mixtureof iso-octyl and dodecyl alcohol. The conversions to the hydroxamatesare all excellent (89-92%). The product of Example VII remains liquid onstanding at room temperature while those of Example V and Example VIsolidify. Addition of 10% water to (V) gives a clear liquid product. Theproduct of Example VI (400 parts) is neutralized with 81 parts of a 30%sulfuric acid (pH 7.0), and the organic layer is separated from theaqueous layer (196 parts with 35% hydroxamic acid content or 90%conversion). The liquid product is again found to be compatible withtall oil fatty acid.

EXAMPLES VIII-IX

Replacement of the decyl alcohol of Example I, all else remaining equal,with (VIII) stearic alcohol or (IX) hexadecyl alcohol results in theproduction of substantially identically appearing compositions.

EXAMPLES X-XIII

The procedure of Example I is again followed except that the methylcaprylate/caprate is replaced by an equivalent amount of (X) methylstearate; (XI) ethyl oleate; (XII) methyl palmitate or (XIII) methylnaphthoate. Similar results are achieved.

EXAMPLE XIV

386 Parts of fresh wet kaolin clay (equivalent to about 300 parts drysolids) are blunged at 65% solids for 5 minutes in a commercial blenderwith water, ammonium hydroxide (to give a final pH of 9.0-9.5), and 0.48part of sodium silicate. A prescribed amount of collector of the presentinvention (or other collector for comparative purposes) is then added tothe well dispersed clay slurry and conditioned in the blender for anadditional 5 minutes. The conditioned pulp is then transferred to a 1.2l flotation cell, diluted with water to about 25% solids, agitated at1000 rpm and floated with carefully regulated air flow (in the range 0.1to 1.5 l/min. of air) for up to 15 minutes.

The floated product containing mostly the anatase impurity and theunfloated, cell product containing the clean and bright clay values arefiltered, dried and assayed for TiO₂ and Fe. The results are set forthin Table I, below:

                                      TABLE I                                     __________________________________________________________________________    Removal of Anatase Impurities from Kaolin Clays                                                          Clay Product                                                         Dosage        Bright-                                                                           % Clay                                    Ex. #                                                                             Collector     Kg/t     % TiO.sub.2                                                                        ness                                                                              Yield                                     __________________________________________________________________________    A   Tall oil fatty acid*                                                                        2        0.6  85.9                                                                                49***                                   B   C.sub.8 carboxylic acid*                                                                    2        1.22 83.4                                                                                65***                                   C   C.sub.12 carboxylic acid                                                                    2        1.01 84.5                                                                              80                                        D   Mixture of C.sub.1 & C.sub.18                                                 carboxylic acids*                                                                            (1.5 + 0.5)**                                                                         0.70 85.5                                                                              70                                        E.sup.x                                                                           C.sub.8 -C.sub.10 hydroxamate                                                 (Methanol Method)                                                                           1        0.22 87.1                                                                              78                                        F.sup.y                                                                           C.sub.8 -C.sub.10 hydroxamate                                                 (Methanol Method)                                                                           1        0.25 88.8                                                                              86                                        G.sup.z                                                                           Sodium octyl hydroxamates                                                     (Soviet Teachings)                                                                          1        0.21 88.0                                                                              68                                        H.sup.z                                                                           C8-C10 hydroxamate                                                                          1        0.25 86.5                                                                              83                                                            0.7    0.71 --  76                                            (Soviet Teachings)                                                                            0.9    0.31 --  77                                        J   H.sup.z + Tall oil fatty                                                                     (10.5 + 1.5)**                                                                        0.20 88.8                                                                              44                                            acid                                                                      K   H.sup.z + decyl alcohol                                                                     (1.2 + 1.0)                                                                            0.17 87.7                                                                              62                                            H.sup.z + decyl alcohol                                                                     (0.47 + 0.39)                                                                          0.37 89.3                                                                              86                                            H.sup.z + decyl alcohol                                                                      (0.7 + 0.58)                                                                          0.19 90.0                                                                              74                                        XV  C.sub.8 -C.sub.10 hydroxamates of                                             Example I      (0.35 + 0.40)**                                                                       0.34 85.0                                                                              87                                        XVI C.sub.8 -C.sub.10 hydroxamates of                                             Example I     (0.48 + 0.54)                                                                          0.28 85.5                                                                              90                                        XVII                                                                              C.sub.8 -C.sub.10 hydroxamates of                                             Example I     (0.55 + 0.63)                                                                          0.24 85.9                                                                              86                                        XVIII                                                                             C.sub.8 -C.sub.10 hydroxamates of                                             Example I     (0.66 + 0.75)                                                                          0.30 89.0                                                                              90                                        XIX C.sub.8 -C.sub.10 hydroxamates of                                             Example I     (0.88 + 0.10)                                                                          0.29 89.5                                                                              90                                        __________________________________________________________________________     *0.77 kg/t of CaCl.sub.2.2H.sub.2 O was added as an activator for fatty       acid flotation of anatase.                                                    **First figure represents hydroxamate dosage; 2nd figure represents decyl     alcohol dosage.                                                               ***Foaming occurs                                                             x & y = products are solid                                                    z = anionic emulsifier used.                                             

The results in Table I demonstrate the superiority of the novelcollectors of the present invention (Examples XV-XIV) over the fattyacids used commercially (Examples A-D ; C₈₋₁₀ hydroxamates of theteachings of the Soviet workers (Examples G and H), and C₈₋₁₀hydroxamates prepared in methanol as in U.S. Pat. No. 4,629,556(Examples E and F). With the use of the novel collector of Example I,the yield of clay is the highest (in the range 86-90%), and the TiO₂impurity in the clay product is low and acceptable (below 0.35%). Thebrightness of the clay product is also quite high (85-89.5). It can bereadily seen from these results that with the other collectors all threerequirements-viz. high yield of clay, low TiO₂, and high brightness-arenot simultaneously satisfied at comparable dosages. In Example F, themetallurgical requirements are satisfied to some extent (although yieldis only 86%), but the dosage of hydroxamate used (1 kg/T) is too highcompared with the hydroxamate dosage of 0.35-0.88 kg/t for the novelcollectors of Examples XV-XIX. A hydroxamate dosage equivalent of about0.5-0.6 kg/t is shown to be sufficient for the novel collector of thepresent invention.

The use of decyl alcohol in conjunction with the C₈₋₁₀ hydroxamatesprepared according to the Soviet teachings improves the metallurgy to aslight degree (compare Example H with example K), but again all threemetallurgical requirements are not concurrently satisfied at comparabledosages thereby indicating that the hydroxamate prepared by followingthe Soviet teachings is inferior.

EXAMPLES XX-XXIV

Following the procedure of Example XIV except that an aged clay isemployed, the following results are obtained.

    ______________________________________                                               Dosage      % Clay   % TiO.sub.2                                       Example                                                                              lb/T real*  Yield    in Clay  Brightness                               ______________________________________                                        XX     0.58        82.6     0.41     86.3                                     XXI    0.77        77.3     0.29     87.2                                     XXII   0.96        75.7     0.28     87.5                                     XXIII  1.15        75.0     0.28     87.6                                     XXIV   1.25        71.4     0.29     87.7                                     ______________________________________                                         *real dosage of hydroxamate equivalent                                   

EXAMPLES XXV-XXVII

The procedure of Examples XX-XXIV is again followed except that thecomposition of Example IV is used and different alcohols are employed inthe hydroxamate production. The results achieved follow:

    ______________________________________                                               Dosage      % Clay     % TiO.sub.2                                     Example                                                                              lb/T real*  Yield      in Clay                                                                              Brightness                               ______________________________________                                        XXV    1.25        62.9       0.23   87.9                                            (isooctanol)                                                           XXVI   1.25        79.2       0.29   87.4                                            (Decanol)                                                              XXVII  1.25        84.7       0.29   87.7                                            (Dodecanol)                                                            ______________________________________                                    

We claim:
 1. In a froth flotation process for beneficiating anon-sulfide ore containing value and impurity minerals comprisingslurrying said ore in an aqueous medium, conditioning said slurry witheffective amounts of a frothing agent and a collector selective for onlyone of said value or impurity minerals and frothing the slurry toproduce a concentrate containing said value minerals by froth flotation,the improvement comprising employing, as the collector, a compositioncomprising a mixture of water, a C₈ -C₂₂ alcohol, a fatty hydroxamicacid salt of 6-22 carbon atoms and an alkali metal sulfate.
 2. A processaccording to claim 1 wherein said alcohol is decyl alcohol.
 3. A processaccording to claim 1 wherein said alcohol is dodecyl alcohol.
 4. Aprocess according to claim 1 wherein a cationic or non-ionic surfactantis also contained in said composition.
 5. A process according to claim 1wherein said composition is in the form of an emulsion.
 6. A processaccording to claim 5 wherein said emulsion is a microemulsion.
 7. Aprocess according to claim 1 wherein said value mineral is a clay.
 8. Aprocess according to claim 7 wherein said clay is a kaolin clay.
 9. In afroth flotation process for beneficiating a non-sulfide ore containingvalue and impurity minerals comprising slurrying said ore in an aqueousmedium, conditioning said slurry with effective amounts of a frothingagent and a collector selective for only one of said value or impurityminerals and frothing said slurry mineral by froth flotation, theimprovement comprising employing as the collector a compositionconsisting of a C₈ -C₂₂ alcohol solution of a fatty hydroxamic acid of6-22 carbon atoms.
 10. A process according to claim 9 wherein saidalcohol is decyl alcohol.
 11. A process according to claim 9 whereinsaid alcohol is dodecyl alcohol.
 12. A process according to claim 9wherein said collector also contains a cationic or non-ionic surfactant.13. A process according to claim 12 wherein said alcohol is decylalcohol.
 14. A process according to claim 12 wherein said alcohol isdodecyl alcohol.
 15. A process according to claim 9 wherein said valuemineral is a clay.
 16. A process according to claim 15 wherein said clayis a kaolin clay.